1. Field of the Invention
The present invention relates to a photoacoustic imaging technique, and more particularly, to a photoacoustic imaging device for filtering two narrowband pulsed laser beams having different wavelength bands from an ultra-broadband pulsed laser beam generated from one light source by a compact, inexpensive mechanical filter to selectively extract the two narrowband pulsed laser beams and measuring oxygen saturation of a measurement object such as a living tissue by using the extracted narrowband pulsed laser beams and an oxygen saturation measurement system using the photoacoustic imaging device.
2. Description of the Related Art
In general, in a living tissue, lesion may be aggravated due to various causes. As the lesion is aggravated, the structure AC00 of the living tissue is changed, or oxygen saturation of inside of structure is also changed.
In order to check the state of the living tissue, an ultrasonic diagnosis method has been used in the related art. In this ultrasonic diagnosis method, the living tissue is irradiated with an ultrasonic wave, and the reflected wave is measured, so that the state of the living tissue is checked. However, due to absorption of a portion of the ultrasonic wave by the living tissue, and thus, the reflected wave is not properly generated. Therefore, there is a problem of low resolution.
In order to solve the problem of low resolution of the ultrasonic diagnosis method, an X-ray diagnosis apparatus may be utilized. However, there is a problem in that the living tissue is exposed to X-ray.
Therefore, there has been required a technique which is harmless to a human body and is able to acquire an accurate, high-resolution image and oxygen saturation of the living tissue. Herein, the oxygen saturation is a percentage of a concentration of oxygenated hemoglobin to a concentration of total hemoglobin inside the tissue.
A technique for complying with this requirement is disclosed in Korean Patent Application Laid-Open No. 10-2013-0033936, titled as “A Photoacoustic Imaging Device Using Near-Infrared Laser”.
The Patent Document discloses a photoacoustic imaging device using a near-infra red laser, including: a probe; a laser emitting unit which is installed in the probe to emit a laser beam with which a living tissue is irradiated; a transducer which is installed to sense an ultrasonic wave instantaneously generated from the living tissue which is irradiated with the laser due to thermal elastic expansion; and a controller which generates a photoacoustic image and an oxygen saturation distribution of the living tissue by using the ultrasonic wave sensed by the transducer and performs a mapping between the generated photoacoustic imaging of the living tissue and the oxygen saturation distribution. Particularly, the laser emitting unit emits two or more different narrowband laser beams.
The two or more narrowband laser beams having different wavelengths are used due to the following reasons.
In general, in measurement of oxygen saturation in blood, two or more narrowband pulsed laser beams are incident on blood, and a concentration of oxygenated blood and a concentration of deoxygenated blood are calculated by using intensities of photoacoustic signals generated wavelength by wavelength and optical absorption coefficients.
However, in order to generate the two or more narrowband pulsed laser beams from one light source, high expensive, complex optical systems such as an OPO (optical parametric oscillator), a dye laser, or a Ti:sapphire laser are required. Accordingly, there is a problem in that the photoacoustic imaging device is highly expensive.
As cited literatures, there are Korean Patent Application Laid-Open Nos. 10-2013-0033936 and 10-2009-0088909.